Heat a little oil in a frying pan, add the spring onions, garlic, chilli and ginger and cook gently for 5 minutes until softened.
Tip into a bowl and leave to cool. Toss the prawns in the cornflour then combine with the cooled onion mixture, pork, sausage meat and oyster sauce.
Lay the pastry sheet out on a lightly floured surface. Roll the filling into a rough sausage shape and lay down one side of the pastry. Brush around the filling with a little beaten egg yolk then roll up into a large sausage roll.
Trim the edges of the pastry then transfer to a tray, cover with clingfilm and refrigerate for 30 minutes until firm. Preheat the oven to 200 degrees Celsius or 400 degrees Fahrenheit.
Cut the sausage roll into 4 then lay on a baking sheet, brush with egg yolk and sprinkle with a little salt. Bake for 20 to 25 minutes until golden brown and risen. Leave to cool slightly then serve with chilli sauce and soy sauce.